JP2012066658A - Earth system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an earth system for reducing high-frequency noise to be caused by operation of an invertor or convertor in a vehicle including the invertor or convertor mounted thereon.SOLUTION: A muffler or an exhaust pipe is grounded to a body. Especially, the muffler hook 2 and a body hook 3 are electrically connected to ground the muffler to the body by connecting a split collar 5 fitted in a hole part 22 of a mount rubber 4 for coupling the muffler hook 2 and the body hook 3 with a lead line 7.

Description

  The present embodiment relates to the technology of the earth system.

  Power converters such as hybrid vehicles such as DC (Direct Current) -AC (Alternating Current) inverters (hereinafter referred to as inverters), DC-DC converters, AC-DC converters (hereinafter collectively referred to as converters) are installed. There is a problem that high-frequency noise is generated in a vehicle, and the high-frequency noise is induced in a radio antenna and is output as a sound signal.

  In order to solve such a problem, the inventor coats a three-phase AC cable (three-phase wire) connecting an IPU (Interigent Power Unit: inverter) and a motor with a braided double shield, thereby providing a three-phase wire. As a result of shielding the electromagnetic wave from, the reduction of high frequency noise was confirmed.

Based on the above results, the cause of such high-frequency noise will be described with reference to FIG. 7 showing a schematic layout of devices in a hybrid vehicle.
As shown in FIG. 7, the hybrid vehicle has an IPU 12. The IPU 12 is a combination of a PCU (Power Control Unit) and a battery, and an inverter (power conversion device) for converting a direct current of the battery (not shown) into an alternating current (three-phase alternating current) sent to the motor 15. ) 13 is provided.
The inverter 13 converts a direct current into an alternating current by switching with an IGBT (Insulated Gate Bipolar Transistor).
The converted alternating current is sent to the motor 15 through the three-phase alternating current cable (three-phase wire 14) to drive the motor 15. The driving motor 15 assists the engine 11. On the other hand, exhaust gas is discharged from the engine 11, and this exhaust gas is discharged to the outside through the exhaust pipe 10. A muffler 1 is provided behind the exhaust pipe 10 to mute the exhaust sound.

Here, in addition to the normal mode current flowing between the inverter 13 (IPU 12) and the motor 15, the common flowing through the body 6 of the vehicle body due to a potential difference between the inverter 13 side and the motor 15 side, stray capacitance, etc. A mode current is generated. As the stray capacitance, a heat sink installed under the inverter 13 and an insulating layer between the inverter 13, a three-phase wire 14 cable itself, a one generated by the motor 15, and the like can be considered.
Accordingly, also in the exhaust pipe 10, a potential difference is generated between the terminal side and the motor 15 side, and a high-frequency current synchronized with the common mode current also flows through the exhaust pipe 10.
Since the exhaust pipe 10 is fixed to the body 6 via an insulating mount rubber, the exhaust pipe 10 is not in contact with the body 6. For this reason, the exhaust pipe 10 is in the same state as the antenna, and radiates an electromagnetic wave due to a high-frequency current synchronized with the common mode current. This electromagnetic wave is considered to be high-frequency noise and noise of radio audio signals.

  In addition, although the high frequency noise resulting from the inverter 13 was demonstrated here, it is possible that a high frequency noise arises similarly by the switching action of a converter.

  In Patent Document 1, an electric unit that generates a three-phase alternating current for driving a motor generator (motor) and a power cable connecting the motor generator are inserted into a metal pipe, and the metal pipe is connected to a vehicle. A vehicle wiring structure that reduces the influence of high-frequency noise caused by a power cable by connecting to a body ground is disclosed.

JP 2010-143436 A

  The technique described in Patent Document 1 does not take measures against a high-frequency current synchronized with the common mode current, and thus cannot be expected to reduce the high-frequency noise generated by the exhaust pipe as an antenna as described above.

  Accordingly, an object of the present invention is to provide an earth system that reduces high-frequency noise.

  The invention according to claim 1 of the present invention for solving the above-mentioned problems is characterized in that, in a vehicle equipped with a power converter, a metal part extending from the power unit of the vehicle is grounded to the body of the vehicle. And

  According to the first aspect of the present invention, since the metallic component extending from the vehicle power unit has the function of an antenna, radiation of high frequency electromagnetic waves can be prevented, so that high frequency noise such as radio can be reduced. It becomes possible.

  According to a second aspect of the present invention, in the earth system according to the first aspect, the power conversion device is an inverter or a converter.

  According to the invention which concerns on Claim 2, an inverter or a converter can be used as a power converter device.

  According to a third aspect of the present invention, in the ground system according to the first or second aspect, the vehicle is a hybrid vehicle or a fuel cell vehicle, and the metallic component is an exhaust for exhausting air from a power unit. It is an exhaust pipe that leads to

  According to a fourth aspect of the present invention, in the earth system according to the first or second aspect, the vehicle is a hybrid vehicle or a fuel cell vehicle, and the metallic component is an exhaust sound from a power unit. It is a muffler that silences.

  According to the invention which concerns on Claim 3 and Claim 4, the earth system of this application is applicable to a hybrid vehicle or a fuel cell vehicle.

  Further, the invention according to claim 5 is the ground system according to claim 4, wherein the muffler has a muffler hook welded to the muffler, and the body has a body hook welded to the body. The muffler hook and the body hook are respectively inserted into holes provided in an insulating mount rubber, so that the muffler is supported by the body, and each of the holes includes A conductor and a cylindrical collar are fitted, the muffler hook and the body hook are in contact with the collar, the collar with which the muffler hook is in contact with the collar with which the body hook is in contact Are connected by lead wires.

  According to the fifth aspect of the present invention, it is possible to reduce high-frequency noise only by exchanging a commonly used mount rubber in fixing the muffler.

  ADVANTAGE OF THE INVENTION According to this invention, the earth system which reduces a high frequency noise can be provided.

It is a figure showing an example of composition of an earth system concerning this embodiment. It is sectional drawing of the mount rubber used for the earth system which concerns on this embodiment. It is a figure which shows another example of the mount rubber used for the earth system which concerns on this embodiment. It is a figure which shows another example of the earth system which concerns on this embodiment. It is a figure which shows the ground location in an exhaust pipe. It is a graph which shows the effect of an earth system in this embodiment. It is a figure which shows the schematic layout of the apparatus in a hybrid vehicle.

  Next, the best mode for carrying out the present invention (referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate. Hereinafter, an example in which the ground system of the present application is applied to a hybrid vehicle having the configuration shown in FIG.

FIG. 1 is a diagram illustrating a configuration example of an earth system according to the present embodiment.
Two muffler hooks 2 having an enlarged diameter portion 21 at the end are welded to the muffler 1 at the upper end of the muffler 1 that is a metallic part extending from the power unit, and the upper end extends to the upper portion. The upper ends of the respective muffler hooks 2 are inserted into holes 22 (see FIG. 2) of the insulating and elastic mount rubber 4. In the example of FIG. 1, the mount rubber 4 has three holes 22, and two muffler hooks 2 penetrate two of them. A body hook 3 connected to the body 6 penetrates through the remaining one hole 22. The body hook 3 also has an enlarged diameter portion 21 at the end.
Each of the hole portions in the mount rubber 4 is fitted with a split collar 5 which is a collar. Details of the split collar 5 will be described later with reference to FIG.

FIG. 2 is a cross-sectional view of a mount rubber used in the earth system according to the present embodiment.
FIG. 2 shows a cross-sectional view of the mount rubber in FIG.
As described above, the mount rubber 4 has the three holes 22. Each hole 22 is fitted with a metal split collar 5. The divided collar 5 is composed of two semi-cylindrical parts, and is formed into a cylindrical shape by combining the two parts.
As shown in FIG. 1, each of the muffler hook 2 and the body hook 3 has an enlarged diameter portion 21 at the tip, and when the muffler hook 2 and the body hook 3 are inserted into the hole portion 22 of the mount rubber 4, this enlarged diameter portion. 21 spreads the joint 23 of the divided color 5. When the enlarged diameter portion 21 penetrates, the split collar 5 is returned by the elastic force of the mount rubber 4 and is in close contact with (attached to) the muffler hook 2 and the body hook 3.
Each of the divided collars 5 attached to the muffler hook 2 and the divided collars 5 attached to the body hook 3 are connected by lead wires 7.
With such a configuration, the muffler hook 2 and the body hook 3 are electrically connected, the muffler 1 and the body 6 are electrically connected, and the muffler 1 is grounded to the body 6.

  Thus, by grounding the muffler 1 to the body 6, a high-frequency current generated due to a common mode current derived from the inverter 13 (FIG. 7) or a converter can flow from the muffler 1 to the body 6. The muffler 1 can be prevented from having an antenna function. Thereby, the high frequency noise radiated | emitted from the muffler 1 can be reduced.

(Another example)
FIG. 3 is a view showing another example of the mount rubber used in the earth system according to the present embodiment. In FIG. 3, the same components as those in FIG.
FIG. 3 is a view showing a portion corresponding to FIG. 2 as another example, and there are two body hooks 3a and two mount rubbers 4a. Each body hook 3a and the mount rubber 4a correspond one-to-one, and each muffler hook 2 also corresponds one-to-one.
The body hook 3a and the muffler hook 2 in each mount rubber 4a are electrically connected via the lead wire 7 with the same configuration as in FIG.

  With the configuration shown in FIGS. 1 to 3, the earth system according to the present embodiment can be constructed simply by replacing the mount rubber that has been generally used in fixing the muffler 1 so far.

(Another example)
FIG. 4 is a diagram illustrating another example of the earth system according to the present embodiment. Here, in FIG. 4, the same components as those in FIG.
1 to 3 grounds the muffler 1 through the lead wires 7 and the split collars 5 in the mount rubbers 4 and 4a. The ground system A1 in FIG. 4 directly connects the muffler hook 2 to the lead wires. The muffler 1 is grounded by connecting to the body 6 at 7a.

(effect)
Hereinafter, the effect of the earth system according to the present embodiment will be described using experimental results.
Up to this point, the method of grounding the muffler 1 to the body 6 as shown in FIGS. 1 to 4 has been described. However, as shown in FIG. 5, each part of the exhaust pipe 10 that is a metallic part is grounded. Also good.
Therefore, in this experiment, as shown in FIG. 5, three places in the exhaust pipe 10 through which exhaust gas is passed from the engine 11 to the muffler 1 are grounded, and surrounding electromagnetic waves are measured. The three grounded locations are the muffler hook (reference numeral 501), the rear wheel front (reference numeral 502), and the exhaust pipe center (reference numeral 503). In addition, the grounding location of the exhaust pipe 10 is not limited to the three locations shown in FIG.
The grounding method used was a method in which the muffler hook 2 (FIGS. 1 to 4) and the exhaust pipe 10 were directly grounded to the body 6 (FIG. 4) using a lead wire 7a (FIG. 4) as shown in FIG.

FIG. 6 is a graph showing the effect of the earth system in the present embodiment.
In the graph in FIG. 6, the horizontal axis indicates frequency (MHz), the vertical axis indicates signal strength (dB), the thick line indicates the signal strength when grounded, and the thin line indicates when the ground is not grounded. Signal strength is shown.

  A thick line 601 in FIG. 6A is a graph showing surrounding electromagnetic waves when the position 501 in FIG. 5 (that is, the muffler hook 2 (FIG. 4)) is grounded to the body 6, and a thin line 602 indicates the body 6. It is a graph which shows the surrounding electromagnetic waves when not grounding to.

A thick line 603 in FIG. 6B is a graph showing surrounding electromagnetic waves when the exhaust pipe 10 (FIG. 5) is grounded to the body 6 at the position 502 in FIG. 5 (that is, in front of the rear wheel). The thin line is a graph showing an electromagnetic wave when the body 6 is not grounded.
A thick line 604 in FIG. 6C is a graph showing surrounding electromagnetic waves when the exhaust pipe 10 (FIG. 5) is grounded to the body 6 at the position 503 in FIG. The thin line is a graph showing an electromagnetic wave when the body 6 is not grounded.

From FIG. 6A and FIG. 6C, it can be seen that the electromagnetic wave tends to decrease as a whole. That is, it can be seen that high-frequency noise is reduced.
Moreover, in FIG.6 (b), it turns out that there exists a tendency for electromagnetic waves to reduce from about 10 MHz to 18 MHz and about 23 MHz to 26 MHz.

(Summary)
As shown in the present embodiment, by installing various portions of the exhaust pipe, it is possible to reduce high-frequency electromagnetic waves originating from the inverter and the converter, and to reduce high-frequency noise of the radio. In particular, when the muffler 1 is grounded, the effect similar to that of grounding the tip of the antenna is produced, and it can be expected that the function of preventing high-frequency noise is enhanced.
In the present embodiment, the exhaust pipe 10 and the muffler 1 are grounded. However, the present invention is not limited to this, and in a vehicle equipped with an inverter, a metal cylindrical part or a bar-like part that is not directly connected to the body is also included. Since there is a possibility of having an antenna function, high frequency noise of the radio can be reduced by grounding these parts to the body.
At this time, in the grounding target such as the exhaust pipe 10, a point that is ½ of the wavelength of the target electromagnetic wave may be grounded.

[For fuel cell vehicles]
In a fuel cell vehicle, a DC current generated by supplying air and hydrogen in a fuel cell, which is a power unit, and a DC current supplied from a battery are converted into a three-phase AC current in a PCU to drive a motor. And offgas is discharged | emitted from the fuel cell through the exhaust pipe and muffler which are metal parts.
Therefore, it is conceivable that high-frequency noise is generated due to a high-frequency current synchronized with the common mode current due to the same cause as that of the hybrid vehicle.
Therefore, for example, it is conceivable that an exhaust pipe made of a metal such as stainless steel operates as an antenna like an exhaust pipe and a muffler in a hybrid vehicle.
Therefore, it can be expected that high-frequency noise can be reduced even if the exhaust pipe of the fuel cell is grounded to the body.

A, A1 Earth system 1 Muffler (metal parts)
2 Muffler hook 3, 3a Body hook 4, 4a Mount rubber 5 Split color (color)
6 Body 7, 7a Lead wire 10 Exhaust pipe (metal parts)
11 Engine 12 IPU
13 Inverter 14 Three-phase wire 15 Motor

Claims (5)

In vehicles equipped with power converters,
A metal system extending from a power unit of the vehicle is grounded to a body of the vehicle. The earth system according to claim 1, wherein the power converter is an inverter or a converter. The vehicle is a hybrid vehicle or a fuel cell vehicle,
The earth system according to claim 1 or 2, wherein the metallic part is an exhaust pipe that guides exhaust from the power unit to the outside of the vehicle. The vehicle is a hybrid vehicle or a fuel cell vehicle,
The earth system according to claim 1 or 2, wherein the metallic part is a muffler that silences exhaust sound from the power unit. The muffler is
Having a muffler hook welded to the muffler;
The body is
Having a body hook welded to the body;
The muffler hook and the body hook are respectively inserted into holes provided in an insulating mount rubber so that the muffler is supported by the body.
Each of the holes is fitted with a conductor and a cylindrical collar,
The muffler hook and the body hook are attached to the collar,
The earth system according to claim 4, wherein the collar to which the muffler hook is attached and the collar to which the body hook is attached are connected by a lead wire.

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